1. Field of the Invention
The present invention relates to a developer support member and an electrophotographic process cartridge for use in an electrophotographic image forming apparatus, as well as an electrophotographic image forming apparatus.
2. Description of the Related Art
In an electrophotographic image forming apparatus, a photosensitive member (drum) is charged by a charging unit, and an electrostatic latent image is formed on the drum by laser. Then, a developer (toner) in a developing container is conveyed by a developer support member, and the electrostatic latent image on the drum is developed by the toner at the portion of the drum to which the developer support member is close. Thereafter, the toner on the drum is transferred to recording paper by a transfer unit, and fixed by heat and pressure. One developer support member for use in such a developing method includes a developer support member in which an elastic layer is provided around a metallic core member and, if necessary, a single surface layer or a plurality of surface layers is/are formed on the elastic layer.
Recently, there has been a demand for higher reproducibility and uniformity of an output image, and in particular, there has been a demand for a developer support member having a highly stabilized toner conveying property. Therefore, there is a need for a developer support member having a toner conveying ability not impaired even after the member is left to stand for a long period under various environments.
In particular, tackiness on a surface of a developer support member may be increased under a high-temperature and high-humidity environment. In this case, a toner in contact with the surface of a developer support member is fixed to the surface to thereby make the toner conveying ability of the developer support member ununiform, thereby sometimes causing defects in an electrophotographic image to be finally formed.
Japanese Patent Application Laid-Open No. 2005-141192 has reported a method for suppressing adverse effects under each temperature and humidity environment by incorporating a polytetramethylene glycol-based polyurethane having a specified composition into a roller surface.
Japanese Patent Application Laid-Open No. 2009-116009 has reported a countermeasure method for suppressing change in surface roughness due to a long period of use of a roller having a surface layer containing flexible polyurethane resin particles.